Obtener el GUID para una EntityReference utilizando complementos en DynamicsCRM

Question

Esta pregunta está en relación con un complemento que ahora estoy creando para Dynamics CRM 2011.

Tengo una entidad que tiene 5 atributos. 1 de estos atributos es una búsqueda para otra entidad.

Lo que estoy tratando de hacer con mi complemento es retener el guía de la entidad de búsqueda. Simple, ¿verdad?

Pero no, me está dando problemas, he probado docenas de formas de usar EntityReference para obtener el GUID pero no puedo. He intentado crear una preimagen que también falló.

Aquí hay un fragmento del código.

Entity entity = (Entity)context.InputParameters["Target"];

   if (entity.LogicalName == "new_producttaxrate")
  {
   if (entity.Attributes.Contains("new_product"))
     {

     EntityReference ownerLookup = (EntityReference)entity.Attributes["new_product"];
      productName = ownerLookup.Name;
      Guid  productId = ownerLookup.Id;

    }
  }

También se le ocurrió esto

     if (entity.Attributes.Contains("new_producttaxrateid"))
              {
                  Guid myGuid = (Guid)entity.Attributes["new_producttaxrateid"];
                  EntityReference ownerLookup = new EntityReference("new_product", myGuid);
                   pid = ownerLookup.Id;
               }

Sigo recibiendo este error

    Unhandled Exception: System.ServiceModel.FaultException`1[[Microsoft.Xrm.Sdk.OrganizationServiceFault, Microsoft.Xrm.Sdk, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]: Condition for attribute 'new_producttaxrate.new_product': expected argument(s) of type 'System.Guid' but received 'System.DBNull'.Detail: 
<OrganizationServiceFault xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.microsoft.com/xrm/2011/Contracts">
  <ErrorCode>-2147220989</ErrorCode>
  <ErrorDetails xmlns:d2p1="http://schemas.datacontract.org/2004/07/System.Collections.Generic">
    <KeyValuePairOfstringanyType>
      <d2p1:key>CallStack</d2p1:key>
      <d2p1:value xmlns:d4p1="http://www.w3.org/2001/XMLSchema" i:type="d4p1:string">   at Microsoft.Crm.Extensibility.VersionedPluginProxyStepBase.Execute(PipelineExecutionContext context)
   at Microsoft.Crm.Extensibility.Pipeline.Execute(PipelineExecutionContext context)
   at Microsoft.Crm.Extensibility.MessageProcessor.Execute(PipelineExecutionContext context)
   at Microsoft.Crm.Extensibility.InternalMessageDispatcher.Execute(PipelineExecutionContext context)
   at Microsoft.Crm.Extensibility.ExternalMessageDispatcher.ExecuteInternal(IInProcessOrganizationServiceFactory serviceFactory, IPlatformMessageDispatcherFactory dispatcherFactory, String messageName, String requestName, Int32 primaryObjectTypeCode, Int32 secondaryObjectTypeCode, ParameterCollection fields, CorrelationToken correlationToken, CallerOriginToken originToken, UserAuth userAuth, Guid callerId, Guid transactionContextId, Int32 invocationSource, Nullable`1 requestId, Version endpointVersion)
   at Microsoft.Crm.Extensibility.OrganizationSdkServiceInternal.ExecuteRequest(OrganizationRequest request, CorrelationToken correlationToken, CallerOriginToken callerOriginToken, WebServiceType serviceType)
   at Microsoft.Crm.Extensibility.OrganizationSdkServiceInternal.Execute(OrganizationRequest request, CorrelationToken correlationToken, CallerOriginToken callerOriginToken, WebServiceType serviceType)</d2p1:value>
    </KeyValuePairOfstringanyType>
  </ErrorDetails>
  <Message>Condition for attribute 'new_producttaxrate.new_product': expected argument(s) of type 'System.Guid' but received 'System.DBNull'.</Message>
  <Timestamp>2011-03-17T13:21:04.6999035Z</Timestamp>
  <InnerFault i:nil="true" />
  <TraceText>

[VATPlugin2: VATPlugin2.TaxRateValidation]
[4b0b7f5c-9950-e011-849d-000c292be099: VATPlugin2.TaxRateValidation: Create of new_producttaxrate]


</TraceText>
</OrganizationServiceFault>

Answer 1

     if (entity.Attributes.Contains("new_product"))
                   {

                       productGUID = ((EntityReference)entity["new_product"]).Id;
                       Entity member = service.Retrieve("product", ((EntityReference)entity["new_product"]).Id, new ColumnSet(true));
                       if (member.Attributes.Contains("name"))
                       {
                           productName = member.Attributes["name"].ToString();
                       }
                   }